Fire grate



Oct. 8, 1935. G. A. MccRoNE FIRE GRATE Filed Aug.. 21,

INVENTOR.

ATfORNEYJ.

Patented Oct. 8, 1935 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to a fire grate.

It is an object of this invention to produce a fire grate that is highly eflicient in that it will promote the combustion of a very high percentage of the combustible fuel which'is fed to it.

This invention also contemplates a fire grate which will not burn up.

A further object of the invention is to produce a fire grate that will not clog by the formation of clinkers and thus will insure a constant supply of air to the burning fuel.

Still another object of the invention is to produce a grate composed of a plurality of identical members which can be very readily assembled,

disassembled or replaced, and which effect a uniform supply of air to a bed of burning fuel.

In the drawing:

Fig. 1 is a longitudinal sectional view through a conventional type of furnace showing the grates in position.

Fig. 2 is a side elevation of one of the grate bars in upright position.

Fig. 3 is likewise the side elevation of an individual grate bar tipped upside down or swung 180 about its lower edge from the position shown in Figure 2.

Fig. 4 is a top plan view of a plurality of grates in assembled relation.

Fig. 5 is a bottom plan View of a plurality of grates in assembled relation.

Fig. 6 is a view along the line 6--6 of Figure 4. Referring more particularly to the drawing, there is shown by way of explanation a conventional type of furnace comprising the boiler I, a combustion chamber 2, an ash pit 3, and an air inlet opening 4all of which are oldand provided with my novel type of grate which may be generally designated 5. The air enters the furnace through air inlet 4, passes upwardly through the grate and the burning fuel. The pathof air and the gases of combustion is indicated by the arrows. The grate 5 is composed of a plurality of iden- 4 tical grate bars 6, such as shown particularly in Figures 2 and 3. Each bar preferably is an iron casting, although it is specifically understood that the bar can be made from any suitable material and by any suitable method. Each grate bar has a body portion I and a head portion 8. The body portion I is provided at each end adjacent its lower edge with the spacing studs 9. The head portion 8 is provided at each end with a conical stud III on the one side and on the other side with spacing lugs I'I having the conical sockets II. The bar 8 is also provided with a plurality v to the strength of the grate bar.

There is always a certain amount of non-com- 1O bustible material in the fuel which settles to the bottom of the burning bed of fuel in the form of clinker, that is, on top of the grate, during combustion in the form of slag or clinker. When the red hot clinker settles down upon the grate 15 it not only shuts off the fiow of air to the burning fuel and thus causes incomplete combustion of the fuel, but it likewise shuts off the air from the upper portion of the grate thus causing the grate to become overheated and eventually de- 20 stroyed, or what is more commonly termed burned out. It is one of the objects of this invention to produce a grate that will not burn out. It has been found that this can be achieved by maintaining a cooling blanket of air at all 25 times between the upper face of the grate and the red hot clinker and/or the bottom of the burning fuel. This cooling blanket of air can be obtained by providing line contacts between the upper face of the grate and the fuel bed. These 30 line contacts can be obtained by fabricating the supporting face of the grate in the form of alternating ridges and valleys, or more specifically by forming the upper face of each grate bar head .8 in the form of an inverted V. The apex of the 35 V extends along the upper face of the head of the grate bar in the form of a longitudinal ridge I3 and the legs of the V form the beveled or in'- clined faces I4 along each side of the ridge I3. The under face I5 of the head 8 is undercut thus 40 forming a-feather edge. The importance of the undercut faces I5 of the head is set forth below. To form a grate for a furnace, such as shown in Figure 1, a plurality of the identical grate bars 6 are placed side by side upon suitable sup- 45 ports such as the angle irons I6, shown in Figure 1. Each grate bar is positioned longitudinally of the furnace. When the bars are placed one adjacent the other the conical studs I0 fit in the conical sockets II, as shown in Figures 4, 5, and 50 6, and the spacing studs of the one bar engage the adjacent face of the opposite bar thus maintaining the. body of the bars in a predetermined, properly spaced relation. At the same time the spacer lugs I 1, each of which has a socket II, 55

space the heads of the adjacent grate bars to produce a small longitudinal crack I 8 between each two adjacent bars, which crack extends approximately -throughout the length of the bars. It will be noted that each crack I8 is. at the bottom of the valley formed by the adjacent beveled faces M of each two adjoining grate bars. It has been found that if the crack I8 is approximately of an inch wide that very efiicient operation of the grate is obtained. However, it is understood that the width of this crack can be varied within limits depending upon the size of the individual grate bar and the type of fuel which is being burned. With a crack of an inch in width it is found that the grate can be operated with a very finely pulverized slack without having unburned fuel fall through the grates into the ash chamber.

During the operation of the grate the slack or pulverized coal will, of course, settle in the valleys formed by the adjacent beveled faces M of adjoining grate bars, but since the air can pass through the pulverized fuel as it flows through the cracks l8, the grate bars will not become overheated. Whatever clinker that may be formed settles down upon the grate bars approximately as shown in Figure 6. It will be noted that the clinker rests upon the ridges 13 of the grate bars thus having roughly a line contact with 'each grate bar, and at the same time an air space 20 is provided between the upper beveled faces M of each two adjoining grate bars and the burning bed of fuel. As'the air comes through the air inlet 4 and is directed upwardly through air passageways 2! between the grate bars and through the cracks 18 by the arcuate baffles I2, it enters the pockets 20 where it is distributed substantially throughout the entire bottom face of the bed of fuel thus effecting efficient combustion. At the same time these pockets of air in the spaces 20 are substantially contiguous and form what practically amounts to a uniform blanket of air between the underside of the clinker and burning fuel bed and the upper faces M of the grate. This blanket of air effectively insulates the grate bars from the terrific heat of the red hot clinker and burning fuel and thus by keeping the bars relatively cool prevents destruction or burning out of the grate bars.

Another important object of this invention is to produce a grate bar that will not clog. This has been accomplished by providing the upper beveled face of each grate bar with a feather edge, 1. e., the under faces l5 of the head 8 of each grate 'bar is undercut or backed away from the longitudinal edges 22 of the head 8. It follows that each two adjoining grate bars form a chamber 2i beneath the cracks I8 of greater width than the cracks 18. Hence, any particle of fuel or clinker which is small enough .to get through the crack l8 will necessarily fall through the chamber 2i into the ash pit. Consequently, there is no possibility of the openings 2! between each two successive grate bars becoming plugged with clinkers and shutting off the flow of air.

Inasmuch as each grate bar 6 is identical with every other grate bar, any size grate can be obtained by placing side by side and/or end to end a greater or less number of grate bars, depending upon the size of the grate desired. The length of the grate bars can also be varied at will. Also, the individual grate bars can be interchanged or replaced by another because but one type of bar is used in fabricating the grate. Since any one bar may be interchanged with any other bar no 5 being in the form of an inverted V thereby providing a grate surface in the form of consecutive'parallel ridges and valleys, each bar having 15 spacing lugs on a side thereof prcviding a narrow slot between adjacent bars extending substantially throughout the length of each valley, each bar having undercut side Walls, a plurality of baiiles extending out from said side walls into 20 the air'passageways formed by the side walls of each two adjacent bars and offset from said nar row slot for directing the infiowing air upwardly between the and through the said narrow slot-to the burning fuel, each baflie having a front '25 face perpendicular to a side wall of the bar and a rear face inclined thereto, the said front and rear faces of each 'ba'ffle intersecting to form an edge which extends downwardly from the side edge'of said slot. 30 2. A grate comprising a plurality of elongated bars, each bar having its upper surface in the form of an inverted V, each bar having a spacing lug for providing a narrow slot between each two consecutive bars extending approximately 35 the length of the bars, a side of each bar being undercut continuously throughout its length from the upper edge thereof whereby the sides of each two consecutive bars form an air passageway of greater width than the said slot to 40 prevent clogging of the passageway by any fuel or ash dropping through the said air slot, and curved baffles on said undercut side extending into the said air passageways for directing the flow of air upwardly through the passageways and air slots, each baflie having a curved front face perpendicular to the side Wall of the bar and a rear face inclined to the side wall of the bar, the front curved face intersecting with the rear inclined face to form a curved edge extend- 50 ing downwardly from an edge of said slot.

3. An elongated grate bar having a head portion with its upper surface comprising two inclined faces forming in section an inverted V, the said surface having uninterrupted parallel side edges, and a depending relatively thinbody portion of less thickness than said head, the underfaces of said head being undercut from the parallel side edges, said body portion having a plurality of curved baffles extending downwardly and offset from said parallel side edges .in zigzag arrangement on the opposite sides of said body, each baffle having a curved front face perpendicular to a side wall of the body portion and a rear face inclined to a side wall of the depending body portion, the said front and rear faces of each curvedbaflie intersecting to form an outer edge extending downwardly from the side edge of the head portion.

GEORGE A. McCRONE. 

